Infiltration cannula

ABSTRACT

An infiltration cannula and method of using the infiltration cannula during an infiltration procedure are disclosed herein. The infiltration cannula includes: a tubular needle and a hub. The tubular needle has a proximal end and a distal end. The tubular needle also has a plurality of apertures disposed in a pattern about the distal end. The apertures are configured to infiltrate fluid into the subcutaneous tissue of a patient. The hub is configured to be held by a person performing the infiltration procedure. The hub has a first end and an opposing second end. The first end is attached to the proximal end of the tubular needle and the second end includes a connector configured to connect to an input source for receiving the fluid to be infiltrated into the subcutaneous tissue of the patient. The fluid flows from the connector, through the hub and into the tubular needle.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] Not Applicable

STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT

[0002] Not Applicable

BACKGROUND OF THE INVENTION

[0003] The present invention relates in general to cannulas and inparticular to an infiltration cannula that allows for intermittentinfiltration of fluids, such as a local anesthetic.

[0004] Many medical procedures require infiltration of fluids, such as alocal anesthetic. One method of infiltration of local anesthetic is viaan infiltration cannula. Infiltrators currently on the market are knownas sprinkler-tip or Klein (the present applicant) needle infiltrators.These cannulas are constructed out of a rigid stainless steel and haveone or more apertures, which are typically round or oval, and aredistributed about the distal end of the cannula. The apertures aredistributed over about 15% to 25% or less than 5.0 cm. of the distal endof the cannula needle. These traditional infiltration cannulas areintended to be inserted through a small incision in the patient's skinand then moved in and out through the subcutaneous tissue while a dilutesolution of local anesthetic (or other pharmaceutical solution) isejected through the distal apertures. Such infiltrators typically have ablunt tip and require the placement of a small hole (made by a one mmskin-biopsy punch or a small surgical blade) through which the blunttipped cannula can be passed. The piston-like in and out motion of thecannula causes the patient discomfort.

[0005] Another method of fluid insertion is via a peripherally insertedcentral catheter, also called a PICC line comprising an elongate plastictube that is placed inside a vein of the patient. PICC lines aretypically used for procedures requiring delivery of fluids over aprolonged period of time. For example, a PICC line may be used when apatient needs to receive intravenous (IV) fluids, such as medication ornutrients over a prolonged period of time, such as a week or more.

[0006] The On-Q® Pain Management System marketed by I-Flow® Corporationemploys a PICC line type system for continuously providing localanesthetic. This system provides prolonged local anesthesia by means ofan elastomer (elastic container) device that continuously infiltrates asolution of local anesthesia over many hours. The On-Q® device is a longsoft flexible tube with many small holes arranged along a significantportion of the tube. The On-Q® device is designed to be positionedwithin a surgical wound at the time of surgery; after the surgical woundis closed the On-Q® device permits slow steady infiltration of a localanesthetic solution into the wound, thereby attenuating post-operativepain. The On-Q® device cannot be inserted through a tiny hole in theskin into subcutaneous tissue. Thus there is a need for a simple devicethat can permit the direct percutaneous insertion of a multi-holedinfiltration cannula into subcutaneous tissue for the localized deliveryof medications such as local anesthetics, chemotherapeutic agents, orcrystalloids for parenteral hydration.

[0007] Traditional techniques for subcutaneous injection of localanesthetic solutions use a high-concentration/low-volume of localanesthetic. This is associated with a rapid systemic absorption of thelocal anesthetic. In order to achieve a prolonged local anestheticeffect, the traditional techniques for using local anestheticsnecessitate either frequent repeated injections or slow continuoussubcutaneous infusion of the local anesthetic. As described above,repeated injections or piston-like movement of the cannula causespatient discomfort. Slow continuous infiltration may not be desirable incertain situations. Furthermore, continuous infiltrations restrictpatient movement for extended periods of time which also cause thepatient discomfort. Thus, there is a need for a system for infiltrationof a local anesthetic into subcutaneous tissue which decreases patientdiscomfort, and allows prolonged local anesthesia.

BRIEF SUMMARY OF THE INVENTION

[0008] An infiltration cannula and method of using the infiltrationcannula during an infiltration procedure are disclosed herein. Theinfiltration cannula includes: a tubular needle and a hub. The tubularneedle has a proximal end and a distal end. The tubular needle also hasa plurality of apertures disposed in a pattern about the distal end. Theapertures are configured to infiltrate fluid into the subcutaneoustissue of a patient. The hub is configured to be held by a personperforming the infiltration procedure. The hub has a first end and anopposing second end. The first end is attached to the proximal end ofthe tubular needle and the second end includes a connector configured toconnect to an input source for receiving the fluid to be infiltratedinto the subcutaneous tissue of the patient. The fluid flows from theconnector, through the hub and into the tubular needle.

[0009] The tubular needle may be manufactured of stainless steel orplastic.

[0010] The apertures may be arranged in a helical pattern or in a spiralpattern.

[0011] The apertures may be distributed over about 33% to about 90% ofthe distal end of the tubular needle.

[0012] The apertures may be round or oval.

[0013] The fluid may be a local anesthetic.

[0014] The infiltration procedure may be performed in conjunction with aliposuction procedure.

[0015] A method of infiltrating fluid into subcutaneous tissue of apatient using an infiltration cannula, such as the one described abovemay include the following steps: (1) inserting an infiltration cannulathrough a patient's skin and into the subcutaneous tissue of the patientat a desired site; (2) receiving fluid from the fluid source via theconnector; (3) transporting the fluid from the connector through the huband into the tubular needle; and (4) ejecting the fluid from the tubularneedle into the subcutaneous tissue of the patient via the apertures.The infiltration cannula used in performing the method includes: aconnector for receiving the fluid from a fluid source, a hub incommunication with the connector and a tubular needle in communicationwith the hub. The tubular needle has a plurality of apertures disposedin a pattern about a distal end. The apertures are configured toinfiltrate the fluid into the subcutaneous the tissue of the patient.

[0016] Steps (1)-(4) may be repeated intermittently. The steps may berepeated at intervals between about eight hours and twelve hours.

[0017] After the desired amount of fluid has been infiltrated at a givensite, the infiltration cannula is removed.

[0018] The infiltration cannula may be inserted at a new site.

[0019] Multiple infiltration cannulas (e.g., two) may be usedsimultaneously. Use of multiple infiltration cannulas preventsdisruption of the method infiltration process when one infiltrationcannula is removed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] These as well as other features of the present invention willbecome more apparent upon reference to the drawings wherein:

[0021]FIG. 1 is a side elevation view of a stainless steel infiltrationcannula shown inserted in subcutaneous tissue shown in partial crosssection;

[0022]FIG. 2 is a section view of the infiltration cannula shown in FIG.1;

[0023]FIG. 3 is a side elevation view of a plastic infiltration cannulashown inserted in subcutaneous tissue shown in partial cross section;

[0024]FIG. 4 is an exploded view of the infiltration cannula shown inFIG. 3; and

[0025]FIG. 5 is a flow diagram illustrating an exemplary procedure forusing an infiltration cannula such as the one shown in FIG. 1 or the oneshown in FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION

[0026] As described in further detail below, the present invention takesadvantage of the tumescent technique in order to provide intermittentinfiltration of local anesthetic. The present invention results in asignificant decrease in patient discomfort due to the elimination of thepiston-like in and out motion of the cannula. Once the cannula is inplace, there is no need to push the cannula through the tissue in orderto deliver the fluid to a wide area. Using the tumescent technique, thetime needed in order to complete the infiltration of a targeted anatomicarea is reduced to nearly half of the time required when usingtraditional prior art cannulas. The device and method described hereincan use multiple (e.g., two) infiltration cannulas simultaneously. Whileone cannula is actively dispersing tumescent fluid into the subcutaneoustissue, the surgeon can reposition a second infiltration cannula. Thisallows the infiltration process to proceed without interruption, whereasprior art techniques of infiltration must be ceased each time thecannula is withdrawn from the skin and re-inserted into anotherdirection.

[0027] The tumescent technique was discovered by Jeffrey Alan Klein,M.D. (the applicant) in 1985. Dr. Klein first published a description ofthe tumescent technique in 1987 when he described the use of dilutelidocaine and epinephrine to permit liposuction totally by localanesthesia. A detailed description of the tumescent technique has notbeen published in anesthesiology literature, and therefore, the uniquebenefits of the tumescent technique are not well recognized byanesthesiologists.

[0028] The tumescent technique is a drug delivery system that takesadvantage of a recently discovered reservoir effect of injecting arelatively large volume of relatively dilute solution of a drug into thesubcutaneous tissue.

[0029] The present invention takes advantage of the tumescent reservoirphenomenon. It has many novel applications, an example of which is painmanagement. This technique eliminates the need for a continuousinfiltration of local anesthetic and allows for intermittent injections.In exemplary embodiments, the intermittent injections are administeredevery eight to twelve hours.

[0030] With the tumescent technique, a large volume of dilute solutionof local anesthesia and epinephrine is injected into the subcutaneousspace resulting in a large bolus (or reservoir) of solution. Theprofound vasoconstrictive effect (shrinking of the capillaries) of thedilute epinephrine produces a dramatic delay in the systemic absorptionof the local anesthetic, which prolongs the anesthetic effects oftumescent anesthesia for eight to sixteen times longer than traditionaltechniques.

[0031] Referring now to the drawings wherein the showings are forpurposes of illustrating preferred embodiments of the present inventiononly, and not for purposes of limiting the same, FIGS. 1 and 2illustrate a stainless steel (reusable) infiltration cannula 10 andFIGS. 3-4 illustrate a (single use) plastic infiltration cannula 30. Thecannula 10, 30 can be inserted under the skin 52 and into thesubcutaneous tissue 50 and tumescent local anesthesia can be infiltratedonce every eight to twelve hours.

[0032] Stainless steel infiltration cannulas 10, such as the one shownin FIGS. 1 and 2, are precision high quality and reusable. Thesecannulas can be used to provide tumescent local anesthesia for surgicalprocedures, such as liposuction, which require tumescent localanesthesia over a relatively large area.

[0033] The cannula 10 includes a tubular needle portion 12 which has aproximal end 14 and a distal end 16. The proximal end 14 of the tubularneedle 12 is attached to a hub 20 that is used by the anesthesiologistor surgeon to hold the cannula 10 during the infiltration procedure. Thehub 20 is connected to the tubular needle 12 at a first end 22 and has aconnector 24, such as a luer lock, at an opposing second end. Theconnector 24 is connected to a fluid source, such as tubing connected toan IV bag. Fluid enters the cannula 10 via the connector 24.

[0034] In exemplary embodiments, the tip at the distal end 16 is closed.The local anesthetic is infiltrated into the patient via apertures 18located proximate the distal end 16 of the tubular needle 12 of thecannula 10. In exemplary embodiments, the apertures 18 are disposedalong the distal end 16 of the cannula 10 in a spiral or helical patternand are distributed over the distal 33% to 90% of the tubular needle 12of the cannula 10. For example, if the length of the tubular needle D is15 cm and the apertures 18 at the distal end 16 cover a length d1 of 5cm, the pattern of apertures of the cannula 10 are distributed over 33%of the tubular needle 12 of the cannula 10.

[0035] The proximal portion 14 of the cannula 10 is devoid of aperturesin order to prevent fluid from leaking out of the cannula insertion sitein the skin.

[0036] Plastic infiltration cannulas 30, such as the one shown in FIGS.3 and 4, are single use cannulas and can be used in one of severalunique ways. First, an anesthesiologist or surgeon can insert aninfiltration cannula 30 with stylet 46 into the subcutaneous tissue 50,remove the stylet 46, then attach an IV tubing to the infiltrator andinject tumescent local anesthesia into the targeted area withoutsubsequent repositioning of the infiltration cannula 30. The plasticflexible nature of the tubular needle 32 of the disposable plasticcannula 30 allows the patient to move or change position of the bodywithout risk of injury that might result if a patient moves while arigid steel cannula is inserted.

[0037] Preferably, the stylet 46 is metal, e.g., stainless steel. Theplastic cannula 30 can be blunt-tipped with the metal stylet tip 48covered by the rounded tip 39 of the plastic cannula 30. Alternatively,the plastic cannula 30 can be open-ended with the stylet 46 extending ashort distance past the end 39 of the plastic cannula. 30. In the caseof an open-ended cannula, the metal stylet 46 can be either blunt-tipped(requiring a skin incision to permit insertion into the subcutaneousspace), or sharp-tipped (permitting the cannula to be inserted directlythrough the skin and into the subcutaneous space without requiring apreparatory skin incision.

[0038] The plastic cannula shown in FIGS. 3 and 4 is similar to an IVcatheter except the sharp hollow stylet used for the insertion of an IVcatheter is replaced by a solid obturator/stylet 46 that can be eithersharp or blunt tipped. Except for the removable stylet 46, the plasticcannula 30 is similar to the stainless steel cannula 10 shown in FIGS. 1and 2 and described above. The plastic cannula 30 includes a flexibletubular needle 32 having a proximal end 34 and a distal end 36. Thedistal end has apertures 38 and the proximal end 34 is devoid ofapertures. As stated above, in exemplary embodiments, the pattern ofapertures 38 in the cannula 30 are distributed over the distal 33% to90% of the tubular needle 32 of the cannula 30. For example, if thetubular needle 32 of cannula 30 shown in FIGS. 3 and 4 has a length D of15 cm and the pattern of apertures are distributed over a length d1 of13.5 cm, then the apertures 38 are distributed over 90% of the cannula.

[0039] A typical infiltration cannula 10, 30 might be 20, 18, 16 or 14gauge (i.e., 20, 18, 16 or 14 cm in length) with small apertures 18, 38placed every 5 mm d2 along the cannula in a spiral or helical pattern.It will be appreciated that the dimensions used herein are exemplary andthat the cannula dimensions, range of gauge, relative size shape andpattern of apertures can vary greatly depending upon clinicalpreference.

[0040] The proximal end 34 of the tubular needle 32 shown in FIGS. 3 and4 is attached to a hub 40 that is used by the anesthesiologist orsurgeon to hold the cannula 30 during the infiltration procedure. Thehub 40 is connected to the tubular needle 32 at a first end 42 and has aconnector 44 at an opposing second end. The connector 44 is connected toa fluid source. As described above and shown in FIG. 4, the stylet 46can be inserted and removed from the cannula 30.

[0041] Infiltration using a plastic infiltration cannula 30, such as theone shown in FIGS. 3 and 4, can be accomplished using an infiltrationpump. Alternatively, the force of gravity could be used to push thetumescent fluid into the tissues by hanging a reservoir plastic bag oftumescent local anesthesia (or other dilute drug, such as achemotherapeutic agent or antibiotics) on an IV pole and connecting bagto the infiltration cannula by an IV line.

[0042] Another application is the injection of tumescent localanesthesia into a localized area through which a surgeon plans to make asurgical incision. The effects of vasoconstriction within the tumescedtissue minimizes surgical bleeding. The effects of tumescent localanesthesia produce prolonged post operative analgesia and also reducethe risk of surgical wound infections.

[0043] Yet another application is to provide an easily accessible routefor systemic administration of crystalloid fluids/electrolytes forsystemic hydration or for other types of drug therapy. Potentialclinical applications include emergency resuscitation with systemicfluids in situations where insertion of an IV catheter into a veincannot be readily achieved. Examples of situations where emergencyaccess for intravenous delivery of fluids might not be possible includeacute trauma or burn wound in civilian or military situations. Anotherapplication might be the emergency treatment of dehydration associatedwith prolonged vomiting or diarrhea (e.g., epidemic cholera) such asamong pediatric patients in rural (e.g., third world) settings. Asubcutaneous infiltration catheter can easily be placed by a layman,whereas inserting an IV catheter into a patient that is severelydehydrated can be difficult even for a skilled physician. Delivery ofsystemic fluids by subcutaneous infiltration is safer in a zero gravitysituation (for example, the Space Station). The addition of a smallamount of capillary vasodilator (e.g., methylnicotinamide) to thesubcutaneous fluid can be used to accelerate the systemic absorption ofthe fluid or drug into the intravascular space.

[0044] The cannula 10, 30 is intended to be inserted far enough throughthe skin 52 so that all of the apertures 18, 38 are within the fat 50 ofthe patient. Once the cannula 10, 30 is properly positioned, it canremain stationary while the local anesthetic (or other pharmaceutical)solution is injected.

[0045] After one portion of the targeted area has been tumesced, theinfiltration is briefly terminated (either by turning off the pump or byclamping the IV tubing) while the cannula 10, 30 is repositioned intoanother area of the subcutaneous tissue. The infiltration is thenrestarted with the cannula stationary in its new position.

[0046] The infiltrator 10, 30 can also be used in the traditional modewhereby the cannula 10, 30 is moved through the targeted tissue whilethe fluid is simultaneously pumped through the cannula 10, 30 and intothe subcutaneous tissue 50.

[0047] Another unique aspect of the tumescent technique's reservoireffect is that one can conveniently achieve a long slow steadyabsorption of a drug delivered to the subcutaneous space 50 usingperiodic injections of a tumescent solution. In certain situations,using a slow IV infusion, the alternative technique, can achieve a slowsystemic absorption of a drug but may be difficult, require greaterclinical expertise, be more expensive, and therefore, less practicalthan the technique described herein.

[0048]FIG. 5 is a flow diagram illustrating steps performed in anexemplary infiltration procedure using a cannula 10, 30 such as the oneshown in FIGS. 1 and 2 or the one shown in FIGS. 3 and 4, respectively.The procedure begins by inserting the tubular needle 12, 32 of theinfiltration cannula 10, 30 into a desired subcutaneous tissue site 50,e.g., via an incision in the patient's skin 52 (block 100). Fluid isthen transported from the fluid source (e.g., an IV bag) into thecannula 10, 30 via the connector 24, 44 that is connected to the fluidsource. The fluid is transported from the connector 24, 44 through thehub 20, 40 and into the tubular needle 12, 32 (block 102). The fluid isthen ejected from the cannula 10, 30 into the subcutaneous tissue 50 ofthe patient via the apertures 18, 38 at the distal end 16, 36 of thetubular needle 12, 34 of the cannula 10, 30 (block 104).

[0049] The fluid is transported (block 102) and ejected (block 104)until infiltration at the current site is completed (yes in decisionblock 106). The fluid can be injected into multiple sites in order todistribute the solution over a greater area.

[0050] Infiltration at a particular site may be deemed complete uponemptying of the fluid source or based on the anesthesiologist orsurgeon's decision to stop the infiltration at the current site. Afterone portion of the targeted area has been tumesced, the infiltration canbe briefly terminated (either by turning off the pump or by clamping theIV tubing) while the cannula 10, 30 is repositioned into another area ofthe subcutaneous tissue. The infiltration is then restarted with thecannula stationary in its new position. If the infiltration at a site iscomplete (yes in decision block 106), the cannula is removed from thecurrent site (block 108). If the infiltration at the current site is notcomplete (no in decision block 106), fluid is transported from the fluidsource (block 102) and ejected into the subcutaneous tissue (block 104)until infiltration at the site is complete (yes in decision block 106).

[0051] If infiltration is complete at the current site (yes in decisionblock 106) but infiltration is not complete (no in decision block 110),the tubular needle 12, 32 of the infiltration cannula 10, 30 is insertedinto a new area of subcutaneous tissue 50. The process described aboveis performed until the infiltration process is complete (yes in decisionblock 110). This process can be repeated intermittently, for exampleevery eight to twelve hours as described above.

[0052] As described above, multiple infiltration cannulas (e.g., can beused at once). Thus, a second cannula can be inserted (block 100) at thesame time as a first cannula is being removed (block 108). Thus, theinfiltration process need not be interrupted in order to reposition asingle cannula.

[0053] Additional modifications and improvements of the presentinvention may also be apparent to those of ordinary skill in the art.Thus, the particular combination of parts described and illustratedherein is intended to represent only a certain embodiment of the presentinvention, and is not intended to serve as a limitation of alternativedevices within the spirit and scope of the invention.

What is claimed is:
 1. An infiltration cannula for use in aninfiltration procedure, the infiltration cannula comprising: a tubularneedle comprising: a proximal end; a distal end; and a plurality ofapertures disposed in a pattern about the distal end, the aperturesconfigured to infiltrate fluid into subcutaneous tissue of a patient;and a hub configured to be held by a person performing the infiltrationprocedure, the hub having a first end and an opposing second end, thefirst end being attached to the proximal end of the tubular needle, thesecond end comprising a connector configured to connect to an inputsource for receiving the fluid to be infiltrated into the subcutaneoustissue of the patient, the fluid flowing from the connector, through thehub and into the tubular needle.
 2. The infiltration cannula as recitedin claim 1, wherein the tubular needle is manufactured of stainlesssteel.
 3. The infiltration cannula as recited in claim 1, wherein thetubular needle is manufactured of plastic.
 4. The infiltration cannulaas recited in claim 1, wherein the apertures are arranged in a helicalpattern.
 5. The infiltration cannula as recited in claim 1, wherein theapertures are arranged in a spiral pattern.
 6. The infiltration cannulaas recited in claim 1, wherein the apertures are distributed over about33% to about 90% of the distal end of the tubular needle.
 7. Theinfiltration cannula as recited in claim 1, wherein the apertures areround.
 8. The infiltration cannula as recited in claim 1, wherein theapertures are oval.
 9. The infiltration cannula as recited in claim 1,wherein the fluid is a local anesthetic.
 10. The infiltration cannula asrecited in claim 9, wherein the infiltration procedure is performed inconjunction with a liposuction procedure.
 11. A method of infiltratingfluid into subcutaneous tissue of a patient, the method comprising: (a)inserting an infiltration cannula through a patient's skin and into thesubcutaneous tissue of the patient at a desired site, the infiltrationcannula comprising a connector for receiving the fluid from a fluidsource, a hub in communication with the connector and a tubular needlein communication with the hub, the tubular needle having a plurality ofapertures disposed in a pattern about a distal end, the aperturesconfigured to infiltrate the fluid into the subcutaneous the tissue ofthe patient; (b) receiving fluid from the fluid source via theconnector; (c) transporting the fluid from the connector through the huband into the tubular needle; and (d) ejecting the fluid from the tubularneedle into the subcutaneous tissue of the patient via the apertures.12. The method recited in claim 11, further comprising repeating (a)-(d)intermittently.
 13. The method recited in claim 12, wherein (a)-(d) arerepeated at intervals between about eight hours and twelve hours. 14.The method recited in claim 12, further comprising removing theinfiltration cannula.
 15. The method recited in claim 14, furthercomprising inserting the infiltration cannula at a new site in thepatient's skin.
 16. The method recited in claim 15, wherein at least twoinfiltration cannulas are inserted into the patient's skin to preventdisruption of the method when one infiltration cannula is removed. 17.The method recited in claim 11, wherein the fluid is a local anesthesia.18. The method recited in claim 17, wherein the method is performed inconjunction with a liposuction procedure.